To quickly parallel park.
The phrase originated from a tactic used to evade the police. The driver, after getting out of view of the police, would rapidly parallel park and duck down so that passing cops would most likely bypass.

The phrase was made famous in Snoop Dogg's song "Drop it Like It's Hot". When he uses the line, he makes a steering motion with his hand, similar to motion taught to drivers learning how to parallel park
"360 to the right, 360 to the left".

"Park It Like It's Hot" then means to park quickly eventhough you aren't being pursued.